The glenoid in total shoulder arthroplasty.

Management of glenohumeral arthrosis with a total shoulder prosthesis is becoming increasingly common. However, failure of the glenoid component remains one of the most common causes for failure. Our understanding of this problem has evolved greatly since the first implants were placed in the 1970's.

The sensitive [SWI (+)] prion: new perspectives on yeast prion diversity.

Yeast prions are heritable protein-based genetic elements which rely on molecular chaperone proteins for stable transmission to cell progeny. Within the past few years, five new prions have been validated and 18 additional putative prions identified in Saccharomyces cerevisiae. The exploration of the physical and biological properties of these "nouveau prions" has begun to reveal the extent of prion diversity in yeast.

A 64-year-old man with chronic obstructive pulmonary disease and an atypical rash.

A 64-year-old male patient with a 15-year history of chronic obstructive pulmonary disease presented with an atypical rash that was refractory to standard therapy. Pulmonary function tests confirmed an obstructive lung disease. Basic laboratory workup revealed conflicting information, leading to a diagnostic challenge discussed in this article.

Cutaneous findings leading to a diagnosis of superior vena cava syndrome: A case report and review of the literature.

Superior vena cava syndrome, which occurs in approximately 15,000 persons in the United States annually, consists of a collection of symptoms and signs resulting from the obstruction of the superior vena cava (SVC). An early and prominent symptom of this condition is a constellation of superficial, dilated, vertically oriented and tortuous cutaneous venules or veins above the ribcage margins, often presenting as a blanchable violaceous eruption. Herein, we report a case of superior vena cava syndrome diagnosed in our dermatology clinic.

[Applications of biologic augmentations in rotator cuff repair].

Biologic augmentation could promote rotator cuff tendon healing and improve the mechanical properties as well as reduce postoperative adhesion. Biologic augmentations play a vital role in rotator cuff repair and healing. However, most of the studies were performed on animals and clinical outcomes were short-term follow-up.

[SWI], the prion formed by the chromatin remodeling factor Swi1, is highly sensitive to alterations in Hsp70 chaperone system activity.

The yeast prion [SWI+], formed of heritable amyloid aggregates of the Swi1 protein, results in a partial loss of function of the SWI/SNF chromatin-remodeling complex, required for the regulation of a diverse set of genes. Our genetic analysis revealed that [SWI+] propagation is highly dependent upon the action of members of the Hsp70 molecular chaperone system, specifically the Hsp70 Ssa, two of its J-protein co-chaperones, Sis1 and Ydj1, and the nucleotide exchange factors of the Hsp110 family (Sse1/2). Notably, while all yeast prions tested thus far require Sis1, [SWI+] is the only one known to require the activity of Ydj1, the most abundant J-protein in yeast.

Symptomatic glenoid loosening complicating total shoulder arthroplasty.

Glenoid component loosening is one of the most common causes of failed total shoulder arthroplasty. Previous reports indicate that it is desirable to reimplant the glenoid component during revision shoulder arthroplasty. The purpose of our study was to retrospectively evaluate the satisfaction of patients undergoing glenoid revision (reimplantation or resection) following total shoulder replacement specifically for symptomatic glenoid loosening.

Ancient gene duplication provided a key molecular step for anaerobic growth of Baker's yeast.

Mitochondria are essential organelles required for a number of key cellular processes. As most mitochondrial proteins are nuclear encoded, their efficient translocation into the organelle is critical. Transport of proteins across the inner membrane is driven by a multicomponent, matrix-localized "import motor," which is based on the activity of the molecular chaperone Hsp70 and a J-protein cochaperone.

Instability after reverse total shoulder replacement.

Background: Despite advances in technique and implant design, instability after reverse total shoulder arthroplasty remains a challenging postoperative complication.

Materials And Methods: We examined our institutions' first 57 reverse total shoulder arthroplasties performed during a 3-year period (2004-2006). There were 9 cases of instability, all occurring within the first 6 months after surgery.

Enucleation following treatment with intravenous pentamidine for Acanthamoeba sclerokeratitis.

Purpose: To describe the course and outcome of treatment of advanced Acanthamoeba sclerokeratitis with intravenous pentamidine.

Methods: A case of advanced Acanthamoeba sclerokeratitis was resistant to conventional therapy and was treated with intravenous pentamidine. The eye was later removed due to incapacitating pain.

Towards a quantitative understanding of mitotic spindle assembly and mechanics.

The 'simple' view of the mitotic spindle is that it self-assembles as a result of microtubules (MTs) randomly searching for chromosomes, after which the spindle length is maintained by a balance of outward tension exerted by molecular motors on the MTs connecting centrosomes and chromosomes, and compression generated by other motors on the MTs connecting the spindle poles. This picture is being challenged now by mounting evidence indicating that spindle assembly and maintenance rely on much more complex interconnected networks of microtubules, molecular motors, chromosomes and regulatory proteins. From an engineering point of view, three design principles of this molecular machine are especially important: the spindle assembles quickly, it assembles accurately, and it is mechanically robust--yet malleable.

Observations on retrieved humeral polyethylene components from reverse total shoulder arthroplasty.

Hypothesis: Analyses of polyethylene components retrieved at revision of total knee, hip, and shoulder replacements have been used to study the effect of design, patient, and surgical factors on initial implant performance, but no studies have reported similar types of findings in retrieved humeral polyethylene components in reverse total shoulder arthroplasty. Our hypothesis is that while the conforming surface of the humeral polyethylene may predispose it to surface wear modalities, as seen in total hip arthroplasty, the presence of clinical instability may also increase the occurrence of focal contact stresses leading to subsurface fatigue failure.

Materials And Methods: Fourteen humeral polyethylene components were retrieved from revision surgery at a single institution.

The HSP70 chaperone machinery: J proteins as drivers of functional specificity.

Heat shock 70 kDa proteins (HSP70s) are ubiquitous molecular chaperones that function in a myriad of biological processes, modulating polypeptide folding, degradation and translocation across membranes, and protein-protein interactions. This multitude of roles is not easily reconciled with the universality of the activity of HSP70s in ATP-dependent client protein-binding and release cycles. Much of the functional diversity of the HSP70s is driven by a diverse class of cofactors: J proteins.

TGFβ2-mediated production of hyaluronan is important for the induction of epicardial cell differentiation and invasion.

In the developing heart, the epicardium is a major source of progenitor cells that contribute to the formation of the coronary vessel system. These epicardial progenitors give rise to the different cellular components of the coronary vasculature by undergoing a number of morphological and physiological changes collectively known as epithelial to mesenchymal transformation (EMT). However, the specific signaling mechanisms that regulate epicardial EMT are yet to be delineated.

Summary of the International Multicenter Prospective Angioedema C1-inhibitor Trials 1 and 2 (IMPACT1 and 2).

Hereditary angioedema (HAE) is an autosomal dominant disease characterized by deficiency of C1 inhibitor (C1-INH) that commonly presents with recurrent swelling affecting different parts of the body. Supplementation with C1-INH is successfully used to treat HAE in selected countries, mostly in Europe. Berinert P (CSL Behring, Marburg, Germany), a human plasma-derived C1-INH, was studied in the International Multicenter Prospective Angioedema C1-inhibitor Trial 1 (IMPACT1) that was completed in 2007.

Co-evolution-driven switch of J-protein specificity towards an Hsp70 partner.

Molecular mechanisms by which protein-protein interactions are preserved or lost after gene duplication are not understood. Taking advantage of the well-studied yeast mtHsp70:J-protein molecular chaperone system, we considered whether changes in partner proteins accompanied specialization of gene duplicates. Here, we report that existence of the Hsp70 Ssq1, which arose by duplication of the gene encoding multifunction mtHsp70 and specializes in iron-sulphur cluster biogenesis, correlates with functional and structural changes in the J domain of its J-protein partner Jac1.

Involvement of the MEKK1 signaling pathway in the regulation of epicardial cell behavior by hyaluronan.

During embryonic development, cells comprising the outermost layer of the heart or epicardium play a critical role in the formation of the coronary vasculature. Thus, uncovering the molecular mechanisms that govern epicardial cell behavior is imperative to better understand the etiology of cardiovascular diseases. In this study, we investigated the function of hyaluronan (HA), a major component of the extracellular matrix, in the modulation of epicardial signaling.

Radiographic and histopathologic analysis of osteolysis after total shoulder arthroplasty.

Hypothesis: This study analyzed clinical, radiographic, and histologic data from failed total shoulder arthroplasties (TSAs) to determine factors associated with osteolysis.

Materials And Methods: From 1985 to 2005, 52 patients (mean age, 61.6 years) underwent revision TSA at a single institution at a mean of 4.

Iron-binding activity in yeast frataxin entails a trade off with stability in the alpha1/beta1 acidic ridge region.

Frataxin is a highly conserved mitochondrial protein whose deficiency in humans results in Friedreich's ataxia (FRDA), an autosomal recessive disorder characterized by progressive ataxia and cardiomyopathy. Although its cellular function is still not fully clear, the fact that frataxin plays a crucial role in Fe-S assembly on the scaffold protein Isu is well accepted. In the present paper, we report the characterization of eight frataxin variants having alterations on two putative functional regions: the alpha1/beta1 acidic ridge and the conserved beta-sheet surface.

The cytosolic J-protein, Jjj1, and Rei1 function in the removal of the pre-60 S subunit factor Arx1.

Although the biogenesis of ribosomal subunits occurs predominantly in the nucleus, final remodeling steps take place in the cytosol. One cytosolic step has two components: 1) the removal of the maturation factor Arx1, which transits from the nucleus to the cytosol with the pre-60 S subunit, and 2) its subsequent transport back into the nucleus. Two cytosolic proteins, Rei1 and Jjj1, are required, but their individual contributions to this step are not understood.

Propionibacterium acnes infection after shoulder arthroplasty: a diagnostic challenge.

Hypothesis: This study reviewed a series of patients diagnosed with Propionibacterium acnes infection after shoulder arthroplasty in order to describe its clinical presentation, the means of diagnosis, and provide options for treatment.

Materials And Methods: From 2002 to 2006, 11 patients diagnosed with P acnes infection after shoulder arthroplasty were retrospectively reviewed and analyzed for (1) clinical diagnosis; (2) laboratory data, including white blood cell count, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP); (3) fever; (4) number of days for laboratory growth of P acnes; (5) organism sensitivities; (6) antibiotic regimen and length of treatment; and (7) surgical management. Infection was diagnosed by 2 positive cultures.